August in Paris - to go or not to go?

In 2008, we lived in the Montmartre area of Paris ... On August 1, we went to our favorite restaurant to discover, much to our dismay, that they would be closed for a month and a half, closing August 1, re-opening September 15. At first I thought, 'How weird, why would anyone close for a month-and-a-half?'
 Paris, France